The perimeter of one face of a cube is 20 cm. Find the volume of the cube?
Appeared in: SGPGI Nursing Officer-2023
Explanation
The perimeter of one face of the cube is given as 20 cm. Since a cube's face is a square, its perimeter is 4 times its side length (a).
By setting 4a = 20 cm, we can calculate the side length 'a' to be 20 / 4 = 5 cm.
The volume of a cube is calculated by cubing its side length (Volume = a³).
Substituting the side length, the volume is 5³ = 5 × 5 × 5 = 125 cm³.
Why Other Options Were Wrong
Option A: This value is incorrect. It may arise from a calculation error, such as incorrectly multiplying the perimeter (20) by the side length (5) and adding the side length again (20*5+20=120), which is not the correct formula for volume.
Option C: This is an incorrect calculation. It does not correspond to the correct formula for the volume of a cube based on the given perimeter.
Option D: This is an incorrect calculation. It might result from a simple arithmetic mistake when trying to compute 5³.
Related Visual
Clinical Relevance
Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Calculating the volume of a cube from the perimeter of one of its faces as background academic context rather than a clinical decision trigger.
While not a direct clinical scenario, this question tests fundamental mathematical and logical reasoning skills essential for nurses.
Nurses frequently use basic math for tasks like calculating medication dosages, IV drip rates, and patient intake/output, where accuracy is critical for patient safety.
What if? If the question gave the total surface area as 150 cm² instead of the face perimeter, you would first find the area of one face (150 / 6 = 25 cm²), then the side length (√25 = 5 cm), leading to the same volume (5³ = 125 cm³).
How to Approach the Question
Identify the given information: The perimeter of one face of a cube is 20 cm.
Recall the properties of a cube. A cube has square faces, and the perimeter of a square is 4 times its side length (a).
Use the given perimeter to calculate the side length of the cube: 4a = 20 cm, so a = 5 cm.
Recall the formula for the volume of a cube: Volume = a³.
Substitute the calculated side length into the volume formula: Volume = 5³ = 125 cm³.
Compare the result with the given options to find the correct answer.
Concept Tested & Keywords
Concept Tested: Calculating the volume of a cube from the perimeter of one of its faces.
Stem keywords: perimeter, face, cube, volume
Lead-in keywords: Find
Question ID
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Practise the full SGPGI Nursing Officer-2023
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